Sheet post-processing apparatus and image forming apparatus

Abstract

A sheet post-processing apparatus includes: an accumulating unit accumulating a sheet having been conveyed; a center-folding unit folding a central portion, in a conveying direction in which the sheet is conveyed, of the sheet, which has been accumulated by the accumulating unit, and a pressing force moving unit that applies a pressing force to the sheet, which has been folded by the center-folding unit, and moves a portion, at which the pressing force is applied, on the sheet in the conveying direction.

What is claimed is: 
     
       1. A sheet post-processing apparatus, comprising:
 an accumulating unit accumulating a sheet having been conveyed; 
 a center-folding unit folding a central portion, in a conveying direction in which the sheet is conveyed, of the sheet, which has been accumulated by the accumulating unit, and 
 a pressing force moving unit including a pair of opposed pressure plates and at least one pressure releasing cam, the pressure force moving unit configured to apply a pressing force to the sheet, which has been folded by the center-folding unit, and moves along a portion of the sheet, at which the pressing force is applied, on the sheet in the conveying direction. 
 
     
     
       2. The sheet post-processing apparatus according to  claim 1 , wherein the pressing force moving unit includes a plurality of pressing force moving units arranged in a direction orthogonal to the conveying direction of the sheet. 
     
     
       3. The sheet post-processing apparatus according to  claim 2 , wherein the at least one pressure releasing cam operationally contacts a surface of the plurality of pressing force moving units. 
     
     
       4. The sheet post-processing apparatus according to  claim 1 , wherein the pressing force moving unit further includes a movable plate having slidability and connected to the at least one pressure releasing cam. 
     
     
       5. The sheet post-processing apparatus according to  claim 1 , wherein the pressing force moving unit includes a rotator. 
     
     
       6. The sheet post-processing apparatus according to  claim 3 , wherein the rotator includes a pair of rotators. 
     
     
       7. The sheet post-processing apparatus according to  claim 1 , wherein the pressing force moving unit includes bearing members at both ends. 
     
     
       8. The sheet post-processing apparatus according to  claim 1 , wherein the center-folding unit has curved shape. 
     
     
       9. An image forming apparatus comprising the sheet post-processing apparatus according to  claim 1 . 
     
     
       10. The sheet post-processing apparatus according to  claim 1 , wherein the pressure plates are configured to be movable in a direction orthogonal to the conveying direction.